There is a lot of good, general information in the article. As with anything, the homeowner should do their due diligence in getting enough information to make an educated decision. Should duct-work be cleaned? YES! Does it need to be cleaned annually or even every second or third year? Not necessarily. It all depends on a bunch of variables. You're right that a well designed and balanced system will deliver the right amount of air flow, but sometimes conditions outside the home/business, make it a necessity to get the ducts cleaned. As for mold? NO filter is going to address a mold issue. If you have mold, you have a moisture issue that needs to be addressed. Also, in my 38 years of experience in the HVAC and sheet metal industries, washable filters are one of the reasons ducts need to be cleaned. They are no where near efficient in cleaning/filtering the air to the level that they should.
I own an HVAC company. Dirt in your ducts stays there and hurts no one. It is like dirt on the ground outside. This industry was infiltrated by a bunch of money grubbing low lifes years ago. As a credible company, we do not clean air ducts. Some who were credible probably signed on not knowing what else to do or to try to make a buck another way. These companies, because they also do HVAC work not only rip off private homeowners, they are ripping off legitimate HVAC company's customers and the integrity of what can and should as a rule be a great service industry. Some probably have gotten into this to simply offer what competitors who were ripping off their customers were offering. Anyone cleaning ducts is in my opinion raising a big red flag that they cannot and should not be trusted. Political pressure from NADCA, advertising dollars, manufacturers and marketers of duct cleaning equipment, and intense competition for the customers is the only reason the government and adverstising companies have not run them out of business and that this cancer perpetuates itself.
The final cost of this service is best determined after a professional inspection. Many air duct cleaning companies build their prices based on individual services, while others offer package pricing which includes such components as the air conditioning and furnace. The following estimates can give you an idea of prices to expect for various services.
Once on the scene, trained Sears professionals utilize powerful, truck-mounted equipment to clear your air ducts of dust, debris, pet dander, allergens, and grime. Our powerful air duct cleaning suction equipment vacuums out years of accumulated dust from your air ducts, leaving them clean and clear. Once finished, our technicians remove all equipment and make sure that your ducts and HVAC unit are restored to their best condition. For continued protection against dirty air ducts, your service technician may suggest a variety of air purification products.
Good article, but it fails to point out that leaky return-side ducts could be drawing dust and allergens into the duct system from the enclosed spaces in which they run, e.g. between walls, below floors, attic. So duct cleaning may only be a temporary solution. The homeowner can get a home energy audit -- free in many states -- to determine if they have significant duct leakage. An Aeroseal dealer may be able to effectively seal up the duct system without needing to tear into walls etc to get to the ducts.
Duct cleaning generally refers to the cleaning of various heating and cooling system components of forced air systems, including the supply and return air ducts and registers, grilles and diffusers, heat exchangers heating and cooling coils, condensate drain pans (drip pans), fan motor and fan housing, and the air handling unit housing (See diagram).